1. Field of the Invention
The present invention relates to an optical touch system and an optical touch-position detection method, and in particular relates to an optical touch system and an optical touch-position detection method adopting a camera to detect the distance and direction of a touch object.
2. Description of the Related Art
Touch techniques applied in displays include not only embedding a capacitive or inductive touch panel into a display device, but also disposing a camera provided with an image sensor to the periphery of the display device to optically detect touch positions.
In a conventional optical touch technique, two cameras are used and disposed at different corners of the touch surface such that the fields of view (FOV) of the two cameras both cover the entire touch surface. The touch position of a touch object at the touch surface is determined by the intersection point of the lines passing through the touch object and the two cameras.
As shown in FIG. 1, camera 101 and 102 are disposed at two corners of the touch area 103 such that the fields of view of the two cameras 101 and 102 both cover the entire touch area 103. A linear light source 104 and a retro-reflector 105 are further disposed at the boundary of the touch area 103. The retro-reflector 105 is located along three edges of the touch area 103 and is capable of reflecting any incident light beam back along its incident direction. Therefore, when the linear light source 104 lightens the entire touch area 103, the light beams are reflected by the retro-reflector 105 to the cameras 101 and 102. In this case, when a touch object touches the touch area 103 to produce a touch point 107, the touch object blocks the reflecting light beams of the directions through the touch point 107 and the cameras 101 and 102, and accordingly the cameras 101 and 102 respectively obtain a dark point at a position on the pixel array of an image sensor provided in the cameras 101 and 102. Finally, a processor 106 acquires the directions of the touch point 107 with respect to the cameras 101 and 102 and calculates the real position of the touch point 107, according to the positions of the dark points on the pixel arrays of the image sensors.
In addition, the conventional optical touch techniques also include a structure wherein a camera and a mirror are disposed at the periphery of the touch surface.
As shown in FIG. 2, a camera 201 is disposed at a corner of a touch area 203 such that the field of view of the camera 201 covers the entire touch area 203. Further, a linear light source 204 and a mirror 205 are disposed along the edges of the touch area 203. Because the camera 201 and the mirror image of the camera 201 are located at the symmetry positions with respect to the mirror 205, this configuration is substantially equal to a two-camera configuration. The linear light source 204 lightens the entire touch area 203 and the mirror 205 reflects light beams to the camera 201. When a touch object touches the touch area 203 to produce a touch point 207, the touch object blocks the light beams of the two directions reflected from the mirror 205 to the camera 201, and accordingly the camera 201 obtains two dark points at two positions on the pixel array of an image sensor provided in the camera 201. Finally, a processor 206 acquires the direction of the touch point 207 with respect to the camera 201 and calculates the real position of the touch point 207, according to the two positions of the two dark points on the pixel array of the image sensor provided in the camera 201.
However, no matter if the configuration has two cameras and a retro-reflector or a camera and a mirror, the manufacturing cost is high. Therefore, the purpose of the invention is to provide an optical touch system and an optical touch-position detection method adopting only one camera to detect touch positions. Therefore, components such as a linear light source, a mirror, and a retro-reflector are not necessary in the optical touch system of the invention. The manufacturing cost on an optical touch system is reduced.